There is a viable business model out there for twitter. In fact, I hinted at it when I wrote about the service for GigaOM way back in September of 2006.
Om is creative in arguing that folks with lots of followers should pay, but as Arrington points out you don’t have control over who starts following you. In classic Scoble form, he chimes in and disagrees with Om but says he would pay.
Twitter users should have the option of having followers pay to get updates. Yes, a monthly subscription. Techcrunch should charge and twitter should get a cut of that monthly fee. All it takes is a handful of entertainment industry types to start touting their subscriber base — the same way the a-list bloggers started comparing who had the longer list of followers — and twitter will actually jump mainstream.
It will also jump back into the mobile sphere where payments could be handled with less friction by the carriers. Everyone wins — consumer gets timely addictive content for a fee, carrier gets money, celebrity gets money (and with enough followers can do secondary marketing promotions), twitter gets money.
Otherwise the twitter experiment is just a recreation of Blogger with less real estate, built in authentication for commenters, and automatic promotion of posts.
On a side note, the web so desperately needs a global public adressing system like twitter’s @replies only where you can @ from a blog or anywhere. Maybe it even looks like an email address like “handle@service” — that might get things closer to something stable and decentralized.